A polypropylene resin has characteristics such as excellent moldability, mechanical physical properties and chemical resistance, thereby being used in various fields such as vehicle interior parts, household appliance parts, industrial materials, textiles or films. However, since the polypropylene resin has relatively low tensile strength and flexural strength, the use thereof in the fields requiring toughness and stiffness such as automotive parts has been limited.
Thus, in order to improve the tensile strength, flexural strength, and impact strength of a polypropylene resin, methods of adding rigid reinforcements such as other polymer resins and rubber components are used, but the general reinforcing materials may have a limitation such that it may not sufficiently improve the mechanical physical properties of the resin.
Further, recently, a glass fiber has been widely used as rigid reinforcements, in order to apply a polypropylene resin to vehicle parts and electric/electronic parts. Since the glass fiber may allow a physical property improvement effect to be obtained with less amount than that of previously used talc, whisker or the like, it has been applied to various fields. However, the polypropylene resin with a glass fiber added may have a problem such that the glass fiber may be broken and scattered, thereby reducing mechanical physical properties.
Recently, various attempts have been made to use not only a glass fiber, but also various microfiber as rigid reinforcements, however, development of a method of reducing scattering of a polypropylene resin and rigid reinforcements, and maintaining or improving mechanical physical properties such as flexural elastic modulus and impact strength to or above a certain level is currently needed.
Although a method of using a carbon fiber as rigid reinforcements has been recently developed, reactivity between a carbon fiber having a reactive functional group on the surface and nonpolar polypropylene may not be substantial, and thus, there also may be a limitation in that the strength of a carbon fiber is hardly reflected on a polypropylene composite. Further, various other additives have been used in order to increase reactivity or compatibility between a carbon fiber and polypropylene, however, the physical property value thereof may be currently of about 50% of a theoretically obtainable value.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.